Latency noticeably increases on laptops when unplugged vs connected to AC power

Neurrone commented 6 years ago

Steps to reproduce:

On battery power, use NVDA normally.

Actual behavior:

There is much higher latency between a keypress, and NVDA's response when plugged in vs running on AC power (a fraction of a second), so much so that it feels unusable and affects your productivity.

Expected behavior:

No noticeable increase in latency when running on battery.

System configuration:

NVDA Installed/portable/running from source:

Installed

NVDA version:

All recent versions of NVDA, including 2018.3.2, alpha-16149,e713f614

Windows version:

Windows 10 1803 and 1709, possibly earlier versions as well

Name and version of other software in use when reproducing the issue:

This is very noticeable on Firefox when browsing, but can be felt when doing anything with NVDA.

Other information about your system:

The default power plan is the balanced plan. Besides the list of settings that you can configure in advanced power plan settings, there are numerous other hidden settings that you can enable and configure, some of which is probably responsible for this behaviour.

I've experienced this on my Thinkpad T480 and an Xps 13 9360, and have heard other reports of this as well.

Other questions:

Does the issue still occur after restarting your PC?

Yes

Have you tried any other versions of NVDA?

Yes

LeonarddeR commented 6 years ago

This issue is not caused by NVDA itself. Therefore, I'm closing this as can't fix. I'd advise to ask for assistance on the users list to have this fixed for your specific cases.

I always base my personal power plan of preference on the high performance plan.

Brian1Gaff commented 6 years ago

Almost certainly a power setting issue I'd say as you surmise. Not very much software makers would be able to do about it though. Its a bit like the old Apple phone slow down system to save on batteries and stopping it just running out of power. I would imagine one needs to find out the monitoring software for power and knobble it, but that will have an effect on battery life, ie how long it can run on the battery.

Even an old core duo xp laptop does this to some extent back in 2013. Brian

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Neurrone commented 6 years ago

@leonardder I realize this can't be fixed within NVDA itself, but was hoping to use this issue as a discussion platform and if necessary, try to get help from Microsoft to resolve this.

jscholes commented 6 years ago

Presumably if your entire system is less responsive on battery, every piece of software will be impacted. So there's not much, if anything, we could discuss here which would be specific to NVDA, unless NVDA is the only piece of software to respond slower to keypresses and every other application continues to work fine.

Neurrone commented 6 years ago

@jscholes yeah, just NVDA, since imperceptible latency is a requirement for productive use. Its a lot like trying to use NVDA with bluetooth headphones.

jscholes commented 6 years ago

So there's no problem in other applications, such as media players, audio games or any other program which can cause your computer to make a noise? Is the responsiveness okay when NVDA is already speaking and you carry out a second action, or while another application is playing audio? This still sounds like a power-related problem that you're only noticing in NVDA because of how you interact with the screen reader.

Brian1Gaff commented 6 years ago

There are some sound drivers that seem to have latency if you do not have the machine make a sound for a few seconds, but this still sounds like a power issue to me. Does the machine use an SSD or a normal hard drive? Brian

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Brian1Gaff commented 6 years ago

Because nvda tends to be in one core of the processor any throttling back will probably be seen more in 32 bit programs I have noticed this with Firefox for example, assuming a good quantity of ram of course.

I'm not up on the latency of the latest version of Narrator, but it would be interesting to find out if this has the same problems. Brian

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valiant8086 commented 6 years ago

Hi.

Find the battery icon on the system tray and hit space on it, this with the balanced power plan in play.

You land on a slider, set this to better performance or best performance. This will mostly resolve the issue you have here. Verified by me personally on a Think Pad t480s which is very similar guts wise to the t480. This setting controls how willing the processor is to clock up and how much it prefers to stay clocked down. Lenovo also has a bad habbit of setting the cpu to be stuck at the maximum clock speed when plugged in on certain models (my t480s did, x1yoga x1 carbon both did). There are solutions, among those is reinstalling windows to rid yourself of any lenovo configurations. Even with all drivers reinstalled my t480s behaves differently than original. The specific explanation for this particular difference may be that you get superb performance plugged in because processor remains clocked at full speed rather than using any sort of stepping, and when on battery, because of the power slider it may be reluctant to step up in favor of power savings and introduce yet more sluggishness. The pegging at max clock speed is an issue too because it generates more heat while plugged in than necessary. I would not have responded here but I don't have any other way to contact you, hope this is helpful.

Cheers: Aaron Spears, A.K.A. valiant8086. General Partner - Valiant Galaxy Associates "We make Very Good Audiogames for the blind community - http://valiantGalaxy.com"

On 10/6/2018 2:21 AM, Dickson Tan wrote:

  Steps to reproduce:
On battery power, use NVDA normally.
  Actual behavior:
There is much higher latency between a keypress, and NVDA's response when plugged in vs running on AC power (a fraction of a second), so much so that it feels unusable and affects your productivity.
  Expected behavior:
No noticeable increase in latency when running on battery.
  System configuration:

    NVDA Installed/portable/running from source:
Installed
    NVDA version:
All recent versions of NVDA, including 2018.3.2, alpha-16149,e713f614
    Windows version:
Windows 10 1803 and 1709, possibly earlier versions as well
    Name and version of other software in use when reproducing the
    issue:
This is very noticeable on Firefox when browsing, but can be felt when doing anything with NVDA.
    Other information about your system:
The default power plan is the balanced plan. Besides the list of settings that you can configure in advanced power plan settings, there are numerous other hidden settings that you can enable and configure, some of which is probably responsible for this behaviour.

I've experienced this on my Thinkpad T480 and an Xps 13 9360, and have heard other reports of this as well.
  Other questions:

    Does the issue still occur after restarting your PC?
Yes
    Have you tried any other versions of NVDA?
Yes

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Neurrone commented 6 years ago

@valiant8086 thanks. I'm interested to find out which setting specifically gets rid of this issue, other than just adjusting the power plan to high performance.

nvaccess / nvda